Thermal control apparatus with signal means



April 15, 1952 J. M. WILSON 2,592,989

THERMAL CONTROL APPARATUS WITH SIGNAL MEANS Filed Oct. 17, 1949 Blmentor JOHN M. WlLSON M WM attorney Patented Apr. 15, 1952 UNITED STATES PATENT OFFICE THERMAL CONTROL APPARATUS WITH SIGNAL S John M. Wilson, Minneapolis, Minn., assignor to Minneapolis-Honeywell Regulator Company, Minneapolis, .Minn., a corporation of Delaware Application October 17, 1949, SerialNo. 121,875

sometimes experienced due to the plug connected to the wall outlets being loose or pulled out and the plug connection between the controller and the blanket is also subject to this same fault. The light furnished .in some blanket controllers will not, of course, operate if the wall plug is pulled out, but if the blanket plug is disconnected the light is, in the prior art devices, not aiiected.

In this latter case, considerable inconvenience .and loss of sleep may result before the difiiculty is discovered. This latter difliculty is quite prevalent for, in the daily making up of the bed, the blanket plug is frequently disconnected. To remedy this situation, the present invention provides, as a primary object, a controller having a .signal means indicating whether or not both of va pair of connection plugs are in place.

It .is a further object to provide a controller having a signal light operable at all times the controller is turned on providing that current is provided and that the controlled device is properly connected.

It is .a further object to provide an improved circuit arrangement for the signal means of an electric blanket controller.

It is a further object to provide .a controller for for .an electrical appliance wherein a signal circuit is completed on the appliance side of a connecting ,plug between the controller and the appliance.

It is a further object to provide a control device manually adjustable to an off position and having means for controlling a signal when so adjusted.

These and other objects will become apparent upon .a study of the following specification and drawings wherein:

Figure 1 is a front elevation of a controller for an electric blanket.

Figure .2 is a section taken on the line 22 of Figure 1 and schematically shows the present circu'it.

Fig. 3 is asimplified schematic wiring diagram of the apparatus of Fig. 2.

Referring to the drawings, controller I .is used to control the energization of an electric heating element II in a "blanket or other appliance l2, said controller being connected to a suitable source of current |3 by a pair of conductors l4 and I5 and a plug connector |6. Likewise, controller I0 is connected to blanket I2 by conductors |'||8 and 30 and an intervening detachable connection means I9.

Controller l0 comprises a lever member 2| 24. The other end of bimetal 24 carries an extension member 25 of insulating material such as Bakelite to which is attached a soft iron armature 26 and switch contacts 21 and 28, said contacts 21 and 28 being connected by a flexible conductor 29 to a terminal member 3|. Contact 28 is arranged to engage stationary contact 32, secured to base 22 by bracket 33, when bimetal 24 is adjusted within its normal operating range and is responding to a relatively low temperature,

said bimetal biasing contact 28 away from 32 on a temperature rise. Permanent magnet 35 is attached to base 22 by a bracket 36 and is arranged to be in registry with and slightly spaced from armature 26 when contacts 28 and 32 are in engagement, this being recognized as a conventional snap action arrangement used to provide positive switching action. Bimetal 24 is adjusted by moving lever 2|, this being accomplished by cam 38 rotatable by a manually adjustable knob or wheel means 39, cam 38 engaging a follower member 4| attached to the right end of lever 2|, follower 4| being held in engagement with cam 38 by a spring 42. Cam 38 is provided with a main portion 43 for adjusting bimetal 24 through its normal operating range and also has a fast rise to a relatively high dwell portion 44 for adjusting said bimetal beyond its normal range. When bimetal 24 is adjusted out of its normal range, and follower 4| is on dwell portion 44, contact 27 engages an additional switch contact 46 carried onbracket 41. Contacts 21 and 46 are used to control a signal light 5| which is in the nature of a very low wattage (about watt) neon bulb, having terminals 52 and 53. A resistor 54 is connected in series with the light 5| and has a resistance value of about 225,000 ohms. To view light 5|, a transparent or translucent lens or bullseye 55 is provided in cover .51 of the controller and light 5| is held in alignment with said lens by a suitable mounting bracket 58. Bimetal 24, in addition to being affected by ambient temperature, is also affected by a conventional anticipating or cycling heater l2 bolted on said bimetal in direct thermal contact therewith, said heater having about 24; ohms resistance, this low resistance giving adequate heating because of the relatively large current for element passing therethrough.

Detachable connector means I9 comprises a member 6| having conductor members 62, 63 and 64 engageable with socket conductor members 65, 66 and 61, respectively, of connector member 58, socket members 66 and 67 being connected to heating element II by wires 20 and 30, respectively, and socket members and 66 being connected together by conductor 69.

Cover 51 of controller Iii has a slot in its front face through which a portion of knob or 3 wheel 39 extends so that it is easily reached for adjustment and so that the indicia on its rim can be read. Obviously, if desired, light I may 'be located in a position to illuminate said indicia.

Because the circuits involved in this apparatus must necessarily be traced in describing its operation, no separate description of said circuit appears to be required.

Operation With controller liI adjusted as shown and with plug I6 connected to a source of current, a circuit may be traced from wire I5 through heater 12,, wire 13, terminal Si, wire TI, terminals 52,

,and '53 of light 5i, resistor 54, wire 73, terminal the current passing therethrough is negligible.

Obviously, element II is not energized because of the open circuit at contact 32.

If knob 39 now be rotated counterclockwise to .some desired value on the indicia scale, cam 38 will move so that follower 4i moves off the high dwell portion 44 and onto the main cam portion 43, thus permitting spring 52 to rotate lever 2! and bimetal 24 clockwise and, assuminga relatively low ambient temperature, moving contact 28 into engagement with contact 32. Upon contact 2T disengaging contact 46, the previously described circuit in parallel with light 5| is 'gopened, hence said light now operates and thereby indicates that plug I6 is properly connected with a source of current and that members 6! and 68 of connector means I9 are connected.

Further, element II is energized by the circuit,

starting with conductor I5 and including heater 12, wire 73, terminal 3 I, wire 29, contacts 2'8 and 32, bracket 33, wire I4, terminal '15, wire I8, conductor members 64 and 61, wire 39, element Ii, wire 29, conductor members 66 and 63, wire II, terminal 'H and wire It back to the current supply. As the current for element I I is now passing through heater 52, it rapidly heats bimetal 2d sufiiciently to warp it upwardly and disengage contacts 28 and 32, thus breaking the energizing circuit for element II. As nothing has taken place to break the circuit for light 5 i, it still operates, contact 46 being spaced beyond the normal off position for bimetal 24.

Upon opening contacts 29 and 32, element II starts cooling and heater I2 and bimetal 24 do likewise until the bimetal again engages con- 'tact 28 with 32 and starts another cycle of operacurrent I3, neither light 5| nor element II can "operate for there is no current available for such operation. Although it is rather rare that plug I8 is pulled out and not replaced, it much more frequently happens that plug 6! is pulled out of 68 and not replaced. With the prior art signal arrangements, assuming that plug I6 is in, it would appear that the apparatus was functioning properly even though connector I9 be disconnected, until the user of the blanket or appliance finds that the device is not working. With the present arrangement, however, disconnection of I9 opens the energizing circuit for light 5I by disconnection of 6265 and 6663 hence, if connector I9, is opened, immediate notice is given by failure of light 5| to operate when knob 39 is adjusted to an on position and steps can be taken to discover the fault.

As a study of the above specification and drawings will reveal many substitutions and equivalents, the scope of the present invention should be determined only by the following claims,

I claim:

1. In control apparatus for an electrical appliance, a controller for said appliance, a first pair of conductors extending into said controller and also connected with connecting means adapted to be connected to a source of current, a second pair of conductors extending from said controller to a detachable connection means arranged between said controller and said appliance, said connection means comprising two separablemembers, one of said members having three projecting conductor means and the other of said members having three corresponding socket conductors arranged to be engaged by said projecting conductors, one of said first pair of conductors being connected to one of said second pair of conductors which in turn is connected to one of first pair of conductors and the other of said second pair of conductors, the other of said second pair of conductors being connected to another of said conductor means of one said connector member, a signal light having a pair of terminals, means connecting one of said terminals to one of said first pair of conductors, a resistor, conductor means including said resistor connecting the other terminal on said light to the remaining conductor means of said one connector member, conductor means connecting the conductor means of the other connector member engageable with said remaining conductor means to the conductor means of said other connector member engageable with the conductor means of said one connector member connected to the other of said first pair of conductors, additional switch means operable upon adjusting said manual adjusting means to its off position, and circuit means controlled by said additional switch means for shunting said signal light.

2. In control apparatus for an electrical appliance, a controller for said appliance, a first pair of conductors connected to said controller and to a connection device adapted to be connected to a source of current, a second pair of conductors extending through a detachable connection for connection to said appliance, one of the conductors of said first pair being connected to a conductor of said second pair in said controller, a switching means connected between the other conductor of said first pair and the other conductor of said second pair, temperature responsive means for operating said switching means, means for manually adjusting the operative relation of said temperature responsive means and said switching means through the normal operating range of said controller, said adjusting means also including means for adjusting said operative relation beyond said normal operating range, second switching means operable to close a circuit as a function of said adjusting means being adjusted out of the operating range of said controller, a signal light in said controller connected to one or" said conductors connected through said controller, a resistor connected to said light, a third conductor extending from said resistor to said detachable connector and connecting to the conductor of said second pair other than the conductor to which said light is connected, and a circuit controlled by said second switching means for shunting said light.

3. In a controller for an electric appliance, a switch means, a temperature responsive means for operating said switch means, manually adjustable cam means having a portion for adjusting the operative relation of said temperature responsive means to said switch means within a normal operating range, a signal means for said controller, additional switch means for controlling said signal means, and an additional cam portion for operating said additional switch means in a manner to effectively deenergize said signal means only when said manually adjustable cam means is adjusted beyond said normal operating range.

4. In control apparatus for an electrical appliance, a controller having a pair of conductors arranged to be connected to a source of current, a second pair of conductors extending from said controller to a detachable connection means adapted to be connected to said appliance, said detachable connection means including a pair of conductor members attached to said second pair of conductors and an additional conductor member, a third conductor extending from said controller to said additional conductor member, a switch in said controller connected between one of said first pair of conductors and one of said second pair of conductors, the other of each of said pairs of conductors being connected together, additional switch means in said controller, a signal light for said controller, means connecting said light to one of said conductors and to said third conductor whereby, when said third conductor member is connected to an opposite one of said conductors on the appliance side of said detachable connection means said light may be energized, and means connecting said additional switch means in controlling relation to said signal light.

5. In control apparatus for an electrical appliance, a controller having a pair of conductors arranged to be connected to a source of current, a second pair of conductors extending from said controller to a detachable connection means adapted to be comiected to said appliance, said detachable connection means including a pair of conductor members attached to said second pair of conductors and an additional conductor member, a third conductor extending from said controller to said additional conductor member, a switch in said controller connected between one of said first pair of conductors and one of said second pair of conductors, the other of each of said pairs of conductors being connected together, a signal light for said controller, means connecting said light to one of said conductors to said third conductor whereby, when said third conductor member is connected to an opposite one of said conductors on the appliance side of said detachable connection means said light may be energized, and second switch means for controlling the energization of said light.

6. In an electric blanket control apparatus, a control device including a switch, a pair of current conductors connected to said device and adapted to be connected to a source of current, three electrical conductors leaving said device, two of said three conductors being connected to said pair of conductors, said switch controlling one of said connections, a signal light in said device, said light being connected to one of said current carrying conductors and to the third conductor leaving said device, circuit means for controlling said light, a detachable coupling member having three conductor means individually connected to said three conductors, said coupling member being adapted to unite with another coupling member having three conductor means and wherein, when two of said last named conductor means are connected together and the two members are in engagement, an energizing circuit for said light will be completed.

7. In control apparatus, a control device including a switch, a pair of current conductors connected to said device and adapted to be con nected to a source of current, three electrical conductors leaving said device, two of said three conductors being connected to said pair of con ductors, said switch controlling one of said connections, a signal light in said device, said light being connected to one of said current carrying conductors and to the third conductor leaving said device, circuit means for controlling said light, a detachable coupling member having three conductor means individually connected to said three conductors, said coupling member being adapted to unite with another coupling member having conductor means and wherein when said two members are connected together the third conductor means and the other of said two conductors are connected together to thereby eomplete an energizing circuit for said light.

8. In a controller for an electrical appliance, switch means for controlling said appliance, condition responsive means for operating said switch means, manually adjustable means for adjusting the operative relation of said condition responsive means to said switch means and having an off position, a signal light for said controller, circuit means independent of said switch means for energizing said light, additional switch means for controlling said light energizing circuit, said additional switch means being adjustable by said manually adjustable means in a manner to efiectively deenergize said light only when said manually adjustable means is in its on" position.

JOHN M. WILSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 12,137 Brach Mar. 22, 1938 9 ,958 Kearsley Apr. 2, 1940 2,433,124 Johnson M Dec. 23. 1947 

